Method and apparatus for perforating in wells



Feb. 11, W69 J. c. M DUFFIE, JR 3,426,850

METHOD AND APPARATUS FOR PERFORATING IN WELLS Original Filed Dec. 15,1958 RY E I H L E R r. NR E P R l M cm. W H" F IIU T TA w s H W F 4 R. eA CC 5 C \u 0 3 0 Ofi c 5.. R O n F E T TD 0 w E0 6 vf 0 EN T S m m 1 UW D I O L L I D M N 1 G I. N U F A C w. G i M L o F q. R 5 O 0 3 II I 23 4 m 4 e 4 4 4 a N n 4 T 2 G E T h a A ml 0 o F v a q 9 K q i a X 4\ aQ AV A 1 X MULTI- CONDUCTOR CABLE REVERSIBLE MOTOR GEAR sox 22 SLIP-RING ASSEMBLY SHIELDED DETECTOR EXTEN SION XMW cu N HOUSING\ A TTORNEY.

United States Patent 3,426,850 METHOD AND APPARATUS FOR PERFORATING INWELLS John C. McDuflie, Jr., Houston, Tex., assignor to Esso ProductionResearch Company Continuation of abandoned application Ser. No. 780,387,Dec. 15, 1958. This application June 20, 1966, Ser. No. 567,794 U.S. Cl.166-255 13 Claims Int. Cl. E21b 47/00, 43/119, 43/116 ABSTRACT OF THEDISCLOSURE A method for perforating in a well bore which contains atleast two spaced-apart pipe strings. In one of the pipe strings adirectional perforator is arranged together with a radiation detectorcapable of detecting radiation from a radiation source located inanother of the pipe strings to provide, upon rotation of the perforatorand radiation detector, indications of the angular position of theradiation source, and thereby the other pipe string, relative to thedirection of perforation.

This application is a continuation of Ser. No. 780,387, now abandoned,entitled, Method and Apparatus for Perforating in Wells, filed Dec. 15,1958, by John C. McDuflie, Jr.

This invention generally concerns multiple zone rwell operations. Moreparticularly, the invention concerns locating pipe strings arranged in aborehole relative to the position of a well tool. In its more particularaspects, the invention concerns locating pipe strings arranged in aborehole relative to the direction of fire of a gun perforator andorienting the gun perforator to direct the fire thereof in a directionaway from one or more of the pipe strings to avoid perforation thereofor toward one or more of the pipe strings to cause perforation thereof.

In multiple zone well operations a plurality of pipe strings arearranged in a borehole which penetrates a plurality of vertically spacedproductive zones and production fluids from each zone are conductedindependently to the earths surface through these pipe strings. In orderto perforate a particular interval, a gun perforator is run in theborehole and fired in a direction to cause penetration of the productiveformation. However, when at least two pipe strings are positionedadjacent the intenval to be perforated it is necessary to direct thefire of the gun perforator to avoid striking and perforating one or moreof the pipe strings other than the pipe string through which the gunperforator is run. Also, in well openations wherein the boreholecontains a plurality of pipe strings it may be desired to direct thefire of the gun perforator to perforate one or more of the pipe strings,as for example, when it is necessary to establish subsurfacecommunication between pipe strings during blowouts, workovers, etc.

These desired results are achieved by the present invention whichprovides method and apparatus for locating pipe strings in a boreholerelative to the direction of fire of a gun perforator, for orienting thegun perforator to direct the fire thereof in any desired circumferentialdirection; and for firing the gun perforator to avoid perforating aparticular pipe or pipes or for perforating a particular pipe or pipesas may be desired. Radioactivity detection techinques are employed tolocate the pipe and particularly the techinque of detecting radiationemitted by radioactive material.

The invention is advantageous in many ways. For example, it avoids theuse of gun guides; it avoids the pos- ICC sibility of an incorrectorientation should a pipe string rotate or slip in a clamp clamping pipestrings together or should the original alignment of the pipe strings bein error; it permits running pipe strings in the Well separately; and itpermits full and constant openings through all of the pipe strings.

These purposes and other purposes of the invention will be apparent froma description thereof taken in conjunction with the drawing wherein:

FIG. 1 is a cross-sectional view of the earths subsurface showing aborehole having arranged therein two pipe strings, one of which containsa tool for perforating and for locating pipe; also shown is a schematicillustration of the surface equipment for rotating the tool, forregistering detection of pipe, and for firing the perforator;

FIG. 2 is a vertical, partly sectional view of the tool of FIG. 1;

FIG. 3 is a plan view of a borehole containing two pipe strings andillustrating one manner of arranging the apparatus according to theinvention; and

FIG. 4 is a plan view of a borehole containing three pipe strings andillustrating one manner of arranging the apparatus according to theinvention.

Referring to the drawing in greater detail, in FIG. 1 is shown aborehole 10 penetrating a subsurface productive formation 11. Twoeccentric, spaced apart pipe strings 12 and 13 are arranged in borehole10 and cemented therein by means of cement 14.

A perforator tool, designated 15, is suspended in pipe string 12 bymeans of a m'ulti-electrical conductor cable 16. Tool 15 includes a toolpositioner and pipe locator section 17 and a perforator section 18connected together by means of flexible joints 19 and extension 33.

As seen in greater detail in FIG. 2, section 17 includes a housing 20 inwhich is arranged a reversible motor 21 to which is connected a gear box22, which in turn is connected to a rotatable shaft 23, to which isconnected a radiation detector 24 and a selsyn motor transmitter 26.Shaft 23 extends through the lower end of housing 20 and connects withthe upper flexible joint 19. Housing 20 is provided with bearings 27which permit shaft 23 to rotate relative to housing 20 and sealing meanssuch as O-ring 29, which is adapted to prevent fluid from enteringhousing 20. Drag springs 28 are arranged on the exterior of housing 20and function to prevent rotation of housing 20 and to centralize thehousing. The latter function is desired in order to maintain consistentradiation detection readings in any direction. Shaft 23 may be providedwith a slip-ring assembly 30 for conducting electrical signalstransmitted through a conductor 31 which is connected to cable 16 toconductors 32' which connect to the gun elements 34 arranged on gunperforator 18, and for conducting electrical signals from detector 24 toconductor 31. A conductor 32 connects cable 16 to motor 21.

Detector 24 is provided with a shield 25 configured so as to col'limatethe detected radiation to confine the area of detection to a limitedarc, as, for example, an arc of 45 of the well bore. This limited arc ofinvestigation is more clearly seen in FIGS. 3 and 4.

As seen in FIGS. 3 and 4, the direction of fire 35 of gun elements 34 isaway from the direction of the arc of detection 36 of the pipes 13 and50 as determined by shield 25.

The surface equipment which electrically connects with cable 16 includesa power supply 40, a selsyn motor receiver 41, a radiation detectorindicator 42, a motor switch 43, and a gun switch 44.

Naturally radioactive or artificially produced radioactive substancesare arranged adjacent to, such as outside of, Within, on, etc., pipestring 13. The radioactive substance may be arranged in any desiredmanner. For example, the interior or exterior of pipe string 13 may becoated with the radioactive substance; or the radioactive substance maybe mixed in the thread-sealing compound used in making up the joint orjoints of pipe string 13; or a fluid or a container containing theradioactive material may be placed or located within pipe string 13. InFIG. 2, the interior of pipe string 13 is provided with a coating ofradioactive material 45.

When it is desired to perforate formation 11, tool 15 is lowered oncable 16 through pipe string 12 until the tool is positioned adjacentformation 11. Motor 21 then is actuated to rotate in one circumferentialdirection by means of motor switch 43. Through reduction gear box 22,shaft 23 rotates slowly, thereby rotating shielded detector 24 andselsyn transmitter 26 mounted thereon. Through extension member 33 andflexible joints 19 connection, gun section 18 is rotated also. Dragsprings 28 maintain housing stationary both vertically and horizontallyduring rotation of these elements. As detector 24 rotates, shieldpermits detector 24 to detect radiation only in a limited are. Whenradiation particles emitted by radioactive material 45 coated on pipestring 13 are detected by detector 24 as evidenced at the detectionindicator 42 on the surface of the earth, the direction of the arc ofdetection 36 may be recorded and observed relative to any rotativeposition of tool 18 established by means of selsyn receiver andtransmitter 41 and 26, respectively. The direction of fire of gunelements 34 is fixed relative to the direction of detection 36.Therefore, locating the pipe string relativeto the direction ofdetection locates the pipe string relative to the direction of fire.Tool 18 then may be rotated by means of motor 21 or, through the selsynmotors, or through separate electrical controls if desired to a positionwherein the direction of fire avoids pipe string 13. Gun elements 34 arefired by means of gun switch 44 once the desired rotational position ofthe gun perforator is obtained. In this case which is illustrated inFIG. 3 wherein only two pipe strings are arranged in the borehole and itis necessary to avoid only the one pipe string 13, the use of selsynmotors may be omitted because since the direction of detection and thedirection of fire are fixed relative to each other once pipe string 13is detected, perforator 18 may be oriented by rotation thereof to directthe gun elements 34 for safe firing. However, in the case illustrated inFIG. 4 wherein an additional pipe string 50 also is positioned in theborehole the positions of each of the pipe strings 13 and 50 may beregistered by the selsyn indicator 41 relative to the rotative positionof tool 18 established by selsyn transmitter 26, and tool 18 may berotated to position the direction of fire 35 of gun elements 34 to avoidthe pipe strings. One manner of operation may be to orient the tool sothat when the direction of detection is positioned between the pipestrings the direction of fire is away from both pipe strings asillustrated in FIG. 4.

If desired, instead of having tool 15 centralized in pipe string 12,biasing means may be employed to bias tool 15 against the wall of pipestring 12. Also, if desired, other retaining means may be employed inconjunction with or in place of drag springs 28.

Any desired radioactive substance may be employed as the radioactivematerial. Examples of such substances are: radon, radium bromide, radiumchloride, uranium bromide, uranium tetrabromide, etc. These arenaturally radioactive substances, however, known artificiallyradioactive substances also may be employed.

Detector 24 may be any device responsive to radiation produced by theradioactive material, for example, it may be a Geiger-Mueller counter,an ionization chamher, or a proportional counter.

Shield 25 is formed of radiation absorbing or moderating material, suchas lead, tungsten, parafiin, boron, cadmium, etc., which material iscapable of absorbing or moderating the radiation being detected.

The invention is applicable to so-called tubingless completions, thatis, wells completed with small diameter pipe called tubing, beingempoyed as borehole casings. This is the type operation illustrated inFIG. 1. However, the invention may also be used in cased and tubedwells, that is, in wells where a casing is run and cemented in place andtubing strings are arranged in the casing. Although the particular typepositioning apparatus, including the reversible motor and the selsynmotors, is a preferred form of apparatus in performing the method of theinvention, other types of apparatus are within the scope of theinvention, for example, a hydraulic type positioning device such asdisclosed and claimed in US. patent application Ser. No. 780,524,entitled, Method and Apparatus for Operating in Wells, filed Dec. 15,1958, by H. S. Arendt, may be employed instead.

The description of the invention is directed to well completionoperations wherein when perforating subsurface intervals it is desiredto avoid pipe strings in the borehole other than the pipe string inwhich the gun perforator is run. However, as mentioned previouslyherein, it may be desired to perforate one or more of the pipe stringsin the borehole other than the pipe string in which the perforator isrun. In this instance, the procedure is similar to the proceduredescribed; however, the gun perforator will be positioned to perforatethe pipe strings rather than to avoid perforation thereof.

The term direction or line of fire is intended to mean, as used herein,one or more directions of fire.

Having fully described the method, apparatus, objects and operation ofmy invention, I claim:

1. A method for perforating in a well bore penetrating a subsurfaceformation, said well bore having arranged therein at least two eccentricspaced-apart pipe strings comprising:

arranging in one pipe string a tool provided with a perforator having aselected direction of perforation and with a detector of radiationhaving a selected direction of radiation detection relative to saidperforator, and with a means capable of causing rotation of said tool;

arranging in at least one other pipe string a source of radiation;

actuating said rotating causing means to rotate said tool to determinean angular position of said radiation source relative to the position ofsaid radiation detector;

further rotating said tool until said direction of perforation thereofrelative to said detector is in a selected direction; and

then actuating said perforator.

2. A method as recited in claim 1 including positioning the direction ofperforation away from the position of said source of radiation.

3. A method as recited in claim 1 including positioning the direction ofperforation toward the position of said source of radiation.

4. A method for perforating in a well bore having arranged therein aplurality of pipe strings comprising the steps of:

arranging in one pipe string a rotatable tool provided with a perforatorhaving a selected direction of perforation and provided with acollimated detector of radiation having a selected direction ofradiation detection fixed relative to said direction of perforation;arranging in at least one other of said pipe strings a source ofradiation capable of emitting radiation detectable by said detector ofradiation;

rotating said tool to a selected angular position thereof as determinedby radiation emitted by said radiation source and detected by saiddetector in order to orient said perforator relative to the position ofsaid other pipe string in which said source of radiation is arranged;and

then actuating said perforator when said tool is in said selectedangular position.

5. A method as recited in claim 4 in which perforation of said pipestring in which said source of radiation is arranged is avoided.

6. A method as recited in claim 4 in which said pipe string in whichsaid source of radiation is arranged is perforated.

7. A method for perforating in a well bore having at least one pipestring arranged therein comprising the steps of:

positioning a source of radiation in one pipe string at a depth in saidwell bore at which it is desired to perforate;

positioning in said well bore external of said pipe string in which saidsource of radiation is positioned a rotatable perforator having aselected direction of perforation and provided with a collimateddetector of radiation capable of detecting radiation emitted by saidradiation source which is indicative of the angular position of saidsource of radiation relative to said direction of perforation;

rotating said perforator to a selected angular position thereof asdetermined by radiation emitted by said source and detected by saiddetector in order to orient said perforator relative to the position ofsaid pipe string in which said source of radiation is arranged; and

then actuating said perforator when said tool is in said selectedangular position.

8. A method as recited in claim 7 in which perforation of said pipestring in which said source of radiation is positioned is avoided.

9. A method as recited in claim 7 in which said pipe string in whichsaid source of radiation is positioned is perforated.

10. A method for perforating in a well bore employing a perforatorhaving perforating axes lying in longitudinally extending planes whereinthe angular disposition of the planes defines a Zone in whichperforations are not produced in one of a plurality of tubing strings insaid well bore comprising the steps of:

disposing a detector of radiation in one of said tubing strings withsaid perforator attached to said detector of radiation;

disposing a radiation source in another of said tubing strings;

obtaining signals from said detector which are representative of energytransmitted between said source and detector and which are indicative ofthe angular position of said source of radiation relative to thedirection of perforation;

simultaneously rotating said perforator and said detector of radiationwhile obtaining said signals to derive an indication of the rotativepositions of said perforator with respect to said other tubing string inwhich said source of radiation is disposed in accordance with which saidperforator may be selectively oriented so that said perforator, whenactuated, avoids perforation of said other tubing string;

selectively orienting said perforator; and

then actuating said perforator.

11. Apparatus for perforating in a well bore having arranged therein aplurality of pipe strings comprising:

a rotatable tool provided wtih a perforator having a selected directionof perforation and with a collimated detector of radiation having aselected direction of radiation detection and with means capable ofcausing rotation of said tool arranged in one of said pipe strings, saiddirection of perforation and said direction of detection being fixedrelative to each other;

a source of radiation arranged in at least one other of said pipestrings;

means at the surface of the earth for indicating the position of saidother pipe string containing said source of radiation relative toangular positions of said rotatable tool; and

means for actuating said perforator.

12. Apparatus as recited in claim 11 in which said means capable ofcausing rotation of said tool includes an electrically operatedreversible motor.

13. Apparatus as recited in claim 11 in which said means for indicatingthe position of said other pipe string relative to angular positions ofsaid rotatable tool includes surface and subsurface arranged selsynmotors.

References Cited UNITED STATES PATENTS 2,781,098 2/1957 Bielstein 166452,785,754 3/1957 True 166-45 3,104,709 9/1963 Kenneday et a1 -4513,154,147 10/1964 Lanmon l66-240 3,165,153 1/1965 Lanmon 1754.513,288,210 11/1966 Bryant 166-35 X 3,294,163 12/1966 Lebourg 175-451 XDAVID H. BROWN, Primary Examiner.

U.S. Cl. X.R. 166297, 313; 175-4.51

